Liquid and vapour-phase antifungal activities of essential oils against Candida albicans and non-albicans Candida [*N.Mandras and A.Nostro contributed equally to this work]

Background. The management of Candida infections faces many problems, such as a limited number of antifungal drugs, toxicity, resistance of Candida to commonly used antifungal drugs, relapse of Candida infections, and the high cost of antifungal drugs. Though azole antifungal agents and derivatives continue to dominate as drugs of choice against Candida infections, there are many available data referring to the anticandidal activity of essential oils (EOs). The aim of this study was to compare the in vitro activity, in vapour state and in liquid phase, of seven essential oils and some related components against clinical yeast isolates of Candida albicans, C.glabrata and C.tropicalis. Fluconazole and voriconazole were used as reference drugs. Methods. The minimum inhibitory concentration and the minimal fungicidal concentration of essential oils and their components were investigated by the broth microdilution method (BM) and the vapour contact assay (VC). Results. The results showed that the EOs anticandidal activity was comparable to that observed with fluconazole and voriconazole. Moreover, EOs activity depended on the assay method used. The inhibiting effects of EOs in vapour phase were generally higher than that in liquid state, except for pine. Thyme red and pine oils showed the better spectrum of activity against all yeasts tested by BM method, whereas thyme red oil, followed by lemon balm, lavender and sage were the most effective by VC method. Carvacrol and thymol exerted an interesting in vitro activity both by BM and VC methods. Many essential oils and their active compounds exhibited anticandidal activity against multidrug resistant strains of Candida spp. Conclusion. These data encourage adequately controlled and randomized clinical investigations. The use in vapour phase could have additional advantages without requiring direct contact, resulting in easy of environmental application such as in hospital, and/or in school.